Shoes need to meet a plurality of technical requirements, such as effectively cushioning ground reaction forces acting on the body, supporting a correct step cycle, and correcting mis-orientations, if necessary. At the same time the shoe, in particular a sports shoe, should be as lightweight as possible, since the energy needed for a course of motion of the shoe is a function of the weight of the shoe. Thus, it is an object of the development of modern sports shoes to meet the described biomechanical requirements and to produce a long-lasting shoe with the lowest possible weight.
In the past, improvements focused on the shoe sole. For example, the assignee of the present application disclosed in issued U.S. Pat. Nos. 5,337,492, 6,920,705, and 7,013,582, and European Application No. EP 0 741 529 A1, the entire disclosures of which are hereby incorporated by reference herein, different sole designs where the commonly used homogenous ethylene-vinyl acetate (EVA) midsole is at least partly replaced by individual elements. In addition, the aforementioned references also disclose the use of cushioning elements that no longer consist of foamed materials, but use elastic framework structures that significantly reduce the weight of the shoe sole and at the same time increase the life of the shoe.
With respect to the design of a shoe in the area above the shoe sole, however, the shoes disclosed in the aforementioned documents use an approach where the shoe upper, starting from the edge of the sole, extends upwardly around the foot. A separate heel cup may be integrated for reinforcing the heel region. For example, assignee's European Patent No. EP 1 048 233 B1, the entire disclosure of which is hereby incorporated by reference herein, discloses a sprint plate having a heel cup integrated into the shoe upper, which serves to improve the performance of the runner. This design of the shoe upper and its interconnection to the sole leads, however, to a shoe having significant weight. Furthermore, a plurality of individual parts must be manually sewn or glued together during manufacture of the shoe, which adds complexity and increases costs.
There is, therefore, a need for a long-lasting shoe, in particular a sports shoe, where the weight above the sole is optimized and, in addition, is particularly easy to produce.